The atomic system is based on a unit of mass, the electron mass (approximately equal to 9.1093897&InvisibleTimes;10-31kilograms), a unit of charge, the electron (approximately equal to 1.60217733&InvisibleTimes;10-19coulombs), a unit of action, the planck (equal to Planck's constant over 2&InvisibleTimes;π), and a unit of electric permittivity written as kappa0 (equal to 1.&InvisibleTimes;107c2farads per meter, or one statfarad per centimeter, where c is the magnitude of the speed of light).

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By taking combinations of these four units, one can derive four units corresponding to the base dimensions length, mass, time, and electric current.

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To facilitate using atomic units, enter the command Units[UseContext](Atomic) so that the second, volt, and tesla refer to the atomic and not SI context.

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When used in conjunction with the UseSystem command, the atomic system sets the following units for the given dimensions. All units have context Atomic.

Dimension Name

Unit Name

mass

electron_mass

electric charge

electron

action

planck

electric permittivity

permittivity

length

bohr

time

second

force

hartree/bohr

energy

hartree

power

hartree per second

electric current

electron per second

electric potential

volt

electric capacitance

square electron per hartree

electric field strength

volt per bohr

electric displacement

electron per bohr squared

electric dipole moment

electron bohr

electric polarizability

electron bohr squared per volt

magnetic permeability

electron_mass bohr per electron squared

magnetic flux

volt second

magnetic flux density

tesla

magnetic inductance

volt second squared per electron

magnetizing force

hartree per tesla bohr cubed

electric dipole moment

hartree per tesla

magnetic polarizability

hartree per tesla squared

Atomic Base Units

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All atomic base units have the context Atomic, including the second, where one atomic second is approximately 2.4188843&InvisibleTimes;10-17SI second.

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